Quantitative Assessment of Carrier Density by Cathodoluminescence. II. Ga As Nanowires
Abstract
Precise control of doping in single nanowires (NWs) is essential for the development of NW-based devices. Here, we investigate a series of MBE-grown Ga As NWs with Be (p -type) and Si (n -type) doping using high-resolution cathodoluminescence (CL) mapping at low and room temperatures. CL spectra are analyzed selectively in different regions of the NWs. Room-temperature luminescence is fitted with the generalized Planck law and an absorption model, and the bandgap and band tail width are extracted. For Be -doped Ga As NWs, the bandgap narrowing provides a quantitative determination of the hole concentration ranging from about 1 ×1018 to 2 ×1019cm-3, in good agreement with the targeted doping levels. High-resolution maps of the hole concentration demonstrate the homogeneous doping in the pure zinc-blende segment. For Si -doped Ga As NWs, the electron Fermi level and the full width at half maximum of low-temperature CL spectra are used to assess the electron concentration to approximately 3 ×1017 to 6 ×1017cm-3. These findings confirm the difficulty in obtaining highly doped n -type Ga As NWs, maybe due to doping compensation. Notably, signatures of high concentration [(5-9)×1018cm-3] at the very top of NWs are unveiled.
- Publication:
-
Physical Review Applied
- Pub Date:
- February 2021
- DOI:
- 10.1103/PhysRevApplied.15.024007
- arXiv:
- arXiv:1909.05602
- Bibcode:
- 2021PhRvP..15b4007C
- Keywords:
-
- Condensed Matter - Materials Science;
- Physics - Applied Physics
- E-Print:
- Phys. Rev. Applied 15, 024007 (2021)